An improved detrended moving-average method for monitoring the depth of anesthesia

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Abstract

The detrended moving-average (DMA) method is a new approach to quantify correlation properties in nonstationary signals with underlying trends. This paper monitored the depth of anesthesia (DoA) using modified DMA (MDMA) method. MDMA provides a power-law relation between the fluctuation function FMDMA(s) and the scale s: FMDMA(s)αsα, where α is the slope of FMDMA(s) in the logarithm scale. We applied the MDMA to monitor the DoA by computing the scaling exponent Fα and Fmin values. To validate the proposed method, we compared our results with the bispectral index (BIS) monitor. We found a close correlation between our results and BIS with r(Fmin ) = 0.9346, r^2 (Fmin ) = 0.9183, and r(Fα) = 0.9458, r^2 (Fα) = 0.8855. Our method reflects the state of consciousness of a patient undergoing general anesthesia faster than BIS as observed clinically. The minimum time delay between the BIS and Fmin trends was 12 s and the maximum was 178 s. Furthermore, in the case of poor signal quality, our results agreed with clinical observation, which indicates that our method can accurately estimate a patient’s hypnotic state in such circumstances. Fα and Fmin trends are responsive and their movement seems similar to changes in the clinical state of the patients.

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• An improved detrended moving-average method for monitoring the depth of anesthesia. (deposited 27 Mar 2011 18:59) [Currently Displayed]